In this study, direct aging (aged‐490 °C/6h) and solution heat treatment and subsequent aging (SHT‐940 °C/2h + 490 °C/6h) heat treatments were applied to Maraging Steel (MS1) produced by Direct Laser Metal Laser Sintering (DMLS) method. The effects of these heat treatments on microstructure, phase transformations, mechanical properties, and corrosion properties in MS1 are given in comparison with the as‐built state. Optical microscope (OM) and scanning electron microscope (SEM) was used for microstructure measurements, Electron Dispersion Spectroscopy (EDX), Differential Scanning Calorimetry (DSC) and X‐ray diffraction (XRD) methods were used to determine the phase transformations. Potentiodynamic polarization tests were applied to determine the corrosion resistance of the material, and stereo optical microscope and the Tafel extrapolation method was used to examine the corrosion results. The hardness test was carried with a Rockwell C method to determine the mechanical character of the material. According to the results obtained, it was determined that the applied heat treatments affect the hardness and corrosion resistance of the material by changing the microstructure and phase transformations of MS1 material produced with DMLS.